Treasury Secretary Steven Mnuchin speaks during a hearing with the House Financial Services Committee on Tuesday. He said that a request from House Democrats for President Trump's tax returns is under review and that "we will follow the law." (Andrew Harrer/Bloomberg News)

House Democrats are giving the Trump administration a hard deadline of April 23 to turn over the president’s tax returns, pushing back against Treasury Secretary Steven Mnuchin’s skepticism over their request for the private records.

Rep. Richard E. Neal (D-Mass.), chairman of the House Ways and Means Committee, on Saturday sent a two-page letter to IRS Commissioner Charles Rettig rebuffing Mnuchin’s statement earlier this week that Treasury would miss House Democrats’ initial April 10 deadline for the returns.

Neal’s latest letter sets the stage for further escalation in the conflict between Congress and the White House, as legal experts have suggested that an outright denial of their request by Mnuchin could be followed by subpoenas or a lawsuit in federal court. Mnuchin so far has only postponed responding to Democrats’ request and said he would confer with the Justice Department, but he has not yet rejected it.

“Please know that, if you fail to comply, your failure will be interpreted as a denial of my request,” Neal’s letter states.

Mnuchin told reporters Saturday that he was trying to move carefully in overseeing a request that raises “very, very complicated” legal questions, emphasizing that his decision could have long-lasting repercussions for future requests by Congress to the IRS. He said that Treasury’s legal office has begun meeting with lawyers in the Department of Justice, but that he has not personally spoken with the attorney general about Trump’s taxes.

“I think it’s more important to the American taxpayers that we get this right than [that] we hit an arbitrary deadline,” Mnuchin said, according to a transcript of his remarks. "I’m not going to make a commitment prematurely as to whether we’ll be able to conclude our legal review within [Neal’s] deadline or not.”

Earlier this month, Neal wrote to the IRS asking for six years of the president’s personal and business tax returns. Trump refused to release his tax returns during the presidential campaign, breaking decades of precedent under which candidates for the White House voluntarily released their returns. Trump claimed it wouldn’t make sense to release his tax returns while, he said, they are under audit.

In his letter, Neal argues that the IRS has an “unambiguous legal obligation” to turn over the returns under section 6103 of the tax code, which states that the treasury secretary “shall furnish” a request from the congressional committees with tax oversight.

Mnuchin revealed in congressional testimony that White House lawyers consulted with Treasury on Trump's tax returns.

“It is not the proper function of the IRS, Treasury, or Justice to question or second guess the motivations of the committee,” Neal wrote in his letter. “Judicial precedent commands that none of the concerns raised can legitimately be used to deny the committee’s request.”

Mnuchin pushed back against that assertion Saturday, saying, “I have responsibility for overseeing the IRS. ... I feel it is my obligation as secretary of Treasury to supervise this.” (The IRS is part of the Treasury Department.)

Attorneys under Neal have been carefully crafting their correspondence with the Treasury Department to improve their odds of winning a subsequent court battle. Some legal experts have speculated that Neal may be trying to improve his case by waiting for an outright denial before leveling additional threats.

“At a certain point, it’s obvious there is not going to be something forthcoming, and at that point, you take further steps,” George K. Yin, a University of Virginia law professor who served as chief of staff for the Joint Committee on Taxation, said in an interview earlier this week. “My inclination is, it’s not yet.”

Jeff SteinJeff Stein is a policy reporter for The Washington Post. He was a crime reporter for the Syracuse Post-Standard and, in 2014, founded the local news nonprofit the Ithaca Voice in Upstate New York. He was also a reporter for Vox. Follow